John boiled in Oil

Here is the link if you have the resource. 

Litfin, Bryan. After Acts: Exploring the Lives and Legends of the Apostles. Chicago, IL: Moody Publishers, 2015. should help

JOHN’S DEATH

A few scattered accounts suggest that John died violently as a martyr, but these sources all come from a time when martyr stories were blossoming everywhere, so they have to be considered suspect.³ Probably they were attempts to expand on Jesus’ assertion in Mark 10:39 that John would drink the cup of the Lord’s suffering. For this reason a noble death had to be invented for John.

In contrast, the church father Tertullian records the story of John being immersed in boiling oil and emerging unscathed. It was at Rome, Tertullian writes, that "the Apostle John was first plunged, unhurt, into boiling oil, and thence remitted to his island-exile" on Patmos (ANF, vol. 3, Prescription Against Heretics 36). Today the alleged spot of John’s boiling at Rome is marked with a chapel called San Giovanni in Oleo, but this story is quite a stretch.

Similar legends were being penned at the same time about Peter and Paul because the early church had a voracious appetite for heroic fiction about their founding figures. This is why the second- or third-century source known as the Acts of John was written (ANF, vol. 8). Although its story of John’s death, in which the apostle lays down in a grave dug by his assistants and calmly expires, is acknowledged to be legendary, the text once again attests a widespread Ephesian tradition for John’s residence in his later life. The earliest and best evidence leans toward a long life for John, not a martydom.

Modern visitors to Turkey can visit the apostolic grave at the ruins of the Basilica of St. John in Selçuk, which is near the ancient site of Ephesus. The church whose ruins are visible today was built by the Byzantine emperor Justinian in the sixth century on top of an earlier chapel from around AD 400. This Byzantine church was once magnificent, with eleven domes on its roof, intricate mosaics on its floors, and a spacious courtyard out front. But did it cover the actual grave of John? Second-century coins were found in the tomb, indicating it may have been a place of Christian veneration quite early. The hillside location is attested as a Roman cemetery. However, there is no firm evidence John’s actual body now lies there, or that it ever truly did.